Communications between distant parties have evolved with an emphasis on more personal and intimate contact between communicants. This emphasis is clearly noted as we observe the shift from written communications (letters and telegraphs) to voice and data communications (telephony) and on to visual communications (video conferencing). However, even with the evolution of video conferencing, communicants still express a need for greater intimacy through eye contact.
Attempts have been made to create eye contact between communicating parties; however, limitations and shortcomings associated with these schemes negate the intimacy and advantages gained in utilizing video communications. In a typical video-conferencing configuration, the video camera and terminal screen are not in line with one another, but are arranged such that a communicating party has the choice of either facing the camera to appear attentive to the distant party or facing the terminal screen to view the image of the distant party. Either choice under this disposition precludes eye-to-eye contact between communicating parties.
One prior attempt to create eye contact entailed placing a half-silvered mirror with a camera behind it within a teleconferencing terminal and a display screen being off to one side. In this set-up, the image radiated onto the display screen of a distant party is reflected by the half-silvered mirror toward the local party, while the image of the local party is passed by the half-silvered mirror and scanned by the camera. Such an arrangement does result in eye contact between parties; however, a number of negative effects result as well.
In changing the internal contents and configuration of the conventional teleconferencing terminals, specially-designed terminals will be required which may render the video-conferencing application cost-prohibitive. Furthermore, given the positioning of the display screen, the image projected to the local party appears recessed into the screen and distant. Therefore, the intimacy gained in achieving eye contact is lost in the recession of the projected image.
Another prior attempt to create eye contact via a new video-conferencing terminal design employed a video projection source, a video camera, a half-silvered mirror and a liquid-crystal screen and is described in L. S. Smoot, U.S. Pat. No. 4,928,301, May 22, 1990. The liquid crystal screen with an excitation at a sufficient control voltage can be rapidly switched from a transparent to a translucent state. This terminal operates in two modes: a capture mode and an image display mode. During the image capture mode, the liquid crystal display is excited such that the front surface screen is made transparent and the video camera detects a head-on image of a local party. During the image display mode, the liquid crystal screen is translucent and serves as a rear-projection screen to display the image of a distant party generated by the video projector source and reflected by the half-silvered mirror. In a teleconferencing system employing two such terminals, synchronization must be maintained between terminals in order to maintain effective communications and eye contact.
This bi-modal operation and configuration of the terminal ensure eye contact between communicating parties; however, as with other previously-developed eye contact structures, there are drawbacks which discourage its practical application. This arrangement requires a new specially-designed terminal which would replace and render useless terminals previously purchased for video conferencing. Furthermore, under this arrangement, synchronization is required to achieve proper communication between terminals. Maintenance of timing between terminals is not required in conventional video-conferencing systems; therefore, the added complexity of synchronization along with other drawbacks imposed by the implementation of this prior terminal outweighs the advantages realized in achieving eye contact and discourages its use.
Other eye contact arrangements have been attempted which require no alterations to video conferencing terminals already in use. In an experiment to assess the relationship between eye contact and a communicant's satisfaction with video conferencing, an apparatus was described using mirrors and cameras to achieve eye contact in the paper Designing Videoconference Facilities for Improved Eye Contact, S. R. Acker and S. R. Levitt, Journal of Broadcasting & Electronic Media, Volume 31, No. 2, Spring, 1987, pp. 181-191. In this arrangement, a half-silvered mirror positioned at an angle of 45.degree. to the video conferencing terminal screen is located between the local party and the video-conferencing terminal in order to combine light paths of the terminal display and camera. This half-silvered mirror reflects the image of the local party to a full-silvered mirror which directs the image into cameras for transmission to a distant terminal. Simultaneously, the image radiated from the terminal screen of a distant party is passed by the half-silvered mirror for viewing by the local party.
Although, this apparatus achieves eye contact with no alterations to existing video-conferencing terminals, the positioning and angling of the mirrors and cameras with respect to one another make the apparatus very bulky and thus not conveniently used in conjunction with an existing terminal screen. Furthermore, an objection to this arrangement is that the display appears to be deeply recessed into the terminal; this is primarily the result of the protrusion distance of the apparatus from the terminal screen.
In view of these drawbacks and shortcomings of prior terminals and apparatus, it is the object of the present invention to provide an apparatus which establishes eye to eye contact between communicating parties without alteration to existing video-conferencing terminals and structured such that more intimate communication between the parties is realized.
In prior Nelson et al U.S. Pat. No. 5,117,285 (hereinafter, U.S. Pat. No. '285) an apparatus for use in video-conferencing applications to establish eye contact between a local party and the image of a distant party appearing on the terminal screen is described. This apparatus comprises polarizers, mirrors, and a camera, and these components are positioned and angled with respect to one another in a special well-defined manner to achieve eye contact such that the apparatus protrudes a minimal distance from the terminal screen.
Internal to this apparatus, a first polarizer and a first mirror are located in line between the local party and the terminal screen. The first polarizer located directly in front of the terminal screen passes a polarization of the image of the distant party radiated from the terminal screen. The first mirror, which is partially silvered, reflects the image of the local party and transmits the image of the distant party that is radiated from the terminal screen and passed by the first polarizer. The reflected image of the local party is directed toward a second mirror located below the first mirror. The second mirror is positioned to capture the image of the local party from the first mirror and to reflect this image into a miniature camera. The second mirror also inadvertently captures light that is transmitted by the first mirror which can cause the camera to pick up an extraneous image of the distant party. A second polarizer, which is cross-polarized with the first polarizer, is located between the second mirror and the camera and serves to minimize the extraneous light of the distant party entering the camera for improved contrast.
The apparatus of U.S. Pat. No. '285 overcomes a number of shortcomings and limitations of other apparatus used to create eye contact. However, an area for improvement of the apparatus of U.S. Pat. No. '285 is the transmissivity of the apparatus. Specifically, because the apparatus of U.S. Pat. No. '285 employs first and second polarizers, each of which passes light having a particular polarization and rejects light of an orthogonal polarization, substantial amounts of light that would otherwise improve the image viewed by the local party and captured by the camera party are rejected and the overall transmissivity of the system is reduced.
Therefore, it is an additional object of our present invention to improve upon the prior apparatus of U.S. Pat. No. '285 and provide an apparatus which establishes eye to eye contact between communicating parties without alteration to existing video-conferencing terminals and structures and without substantial reduction in the transmissivity, such that more intimate communication between the parties is realized.